I am dynamically storing data from different data recorders in timetables, nested in a structure DATA, such as DATA.Motor (timetable with motor data), DATA.Actuators (timetable with actuators data) and so on.
My objective is to have a function that synchronizes and merges these timetables so I can work with one big timetable.
I am trying to use synchronize to merge and synchronize those timetables:
fields = fieldnames(DATA);
TT = synchronize(DATA.(fields{1:end}));
but get the following error:
Expected one output from a curly brace or dot indexing expression, but there were 3 results.
This confuses me because DATA.(fields{1}) return the timetable of the first field name of the DATA structure.
Any thought on how I can solve this is greatly appreciated.
The problem here is that fields{1:end} is returning a "comma-separated list", and you're not allowed to use one of those as a struct dot-index expression. I.e. it's as if you tried the following, which is not legal:
DATA.('Motor','Actuators')
One way to fix this is to pull out the values from DATA into a cell array, and then you can use {:} indexing to generate the comma-separated list as input to synchronize, like this:
DATA = struct('Motor', timetable(datetime, rand), ...
'Actuators', timetable(datetime, rand));
DATA_c = struct2cell(DATA);
TT = synchronize(DATA_c{:});
Related
I have large data sets which i want to work with in matlab.
I have a struct called Trail containing serveral structures called trail1, trail2 ...
which then contain several matrices. I now want to add another point to for instance trail1
I can do that with Trail.trail1.a2rotated(i,:) = rotpoint'; the problem is that i have to do it in a loop where the trail number as well as the a2rotated changes to e.g. a3rot...
I tired to do it like that
name ="trail"+num2str(z)+".a2rotated"+"("+i+",:)";
name = convertStringsToChars(name);
Trail.(name) = rotpoint'
But that gives me the error: Invalid field name: 'trail1.a2rotated(1,:)'.
Does someone have a solution?
The name in between brackets after the dot must be the name of a field of the struct. Other indexing operations must be done separately:
Trail.("trail"+z).a2rotated(i,:)
But you might be better off making trail(z) an array instead of separate fields with a number in the name.
I'm relatively new to matlab and would really appreciate any help.
Currently, I have a function (we'll call it readf) that reads in data from a single ascii file into a struct of multiple fields (we'll call it cdata).
names = cellstr(char('A','B','C','D','E','F','G'));
cdata = readf('filestring','dataNames',names);
The function works fine and gives me the correct output of a struct with these field names, with the value of each field name being a cell array of the corresponding data.
My task is to create a for loop that uses this readf function to read in a folder of these ascii files at once. I'm trying to work it so that the for loop creates a struct with an index of the different cdata structs. After trying a few different methods, I am stumped.
This is what I have so far.
files = struct2cell(dir('folderstring')); %creates a cell array of the names of the files withing the folder
for ii=length(files);
cdata(ii) = readf([folderstring,files(1,1:ii),names],'dataName',names);
end;
This is currently giving me the following error.
"Error using horzcat
Dimensions of matrices being concatenated are not consistent."
I am not sure what is wrong. How can I fix this code so i can read in all the data from a folder at once??? Is there a better and more efficient way to do this than making an index to this struct? Perhaps a cell array of different structures or even a structure of nested structures? Thanks!
Change:
for ii=length(files);
cdata(ii) = readf([folderstring,files(1,1:ii),names],'dataName',names);
end;
To:
for ii=1:length(files); % CHECK to make sure length(files) is giving you the right number
cdata(ii) = readf([folderstring,files{ii},names],'dataName',names);
end;
% CHECK files{ii}, with 1,2,3 etc. is giving you the correct file name.
I have a <850x1> cell called x. Each of the individual structures has a 'Tag' name and 'Data' cell with <7168x1 double> data values.
(i.e.
x{1,1}.Tag = 'Channel1', x{1,1}.Data= <7168x1 double>)
So, I want to go through the x cell, identify the structures with 'Channel1' Tag names and pull out that structure's data. Then, combine the data into a cell called Ch1. Here is my approach so far:
n=1:850
if x{n,1}.Tag == 'Channel1'
Ch1{:,n} = x{n,1}.Data;
end
However, this gives an error: Bad cell reference operation.
Any ideas what may be going wrong?
There are 2 issues here. First, your if statement will compare each entry in the string x{n,1}.Tag to each entry in the string 'Channel1'. If the dimensions are not the same, you will get an error. To fix this, you could use the string compare function, strcmp. The other issue is that you are assigning n to all values between 1 and 850 at once. This is the issue that is producing the actual error you are seeing. Instead, you want to step through each of these values one at a time with a for loop. I would suggest trying the following code:
for n=1:850
if strcmp(x{n,1}.Tag, 'Channel1')
Ch1{:,n} = x{n,1}.Data;
end
end
Let me describe the question in this way. I have a .mat file, and if I open it, it contains a 1x10 struct data. In each data, it has a 1x5 struct (or field) called res. In res, it has a 1x1 struct (or field) called, let's say, foo. Thus, I have ixj copies of data(i).res(j).foo .
Is there anyway I can change the name of this foo? say I want all data(i).res(j).foo to become data(i).res(j).bar
I did search on the internet, and tried a few ways (add field and delete, create a temp field, use cell2field or fieldtofile, etc.) and all of them didn't work. The most frequent returned error is "Subscripted Assignment between dissimilar structures."
Please help, thanks in advance!
The safest way is probably by looping over data twice, the first pass creating a new field bar for each subfield like data(i).res(j).bar=data(i).res(j).foo, then the second pass deletes the old fields like data(i).res(j) = rmfield(data(i).res(j),'foo').
Thanks caoy and NotLikeThat. I finally came to an conclusion.
data2 = data
for i=1:10
for j = 1:5
data(i).res(j).bar = data2(i).res(j).foo;
end
data(i).res = rmfield(data(i).res, 'foo');
end
I probably need to removed i, j, and data2 after running this script.
I previously posted on how to display and access structure array content. The file consisted of states, capitals, and populations. Now I'm having trouble in created a new structure by organizing these states in alphabetical order. I did this by the sortrows function, and I tried pairing up the values of population and the capitals with the alphabetical states, but I can't seem to get it to be an array. I want it to be an array so I can write it to a file. This is what I have so far:
fid=fopen('Regions_list.txt')
file=textscan(fid,'%s %s %f','delimiter',',')
State=file{1}
Capital=file{2}
Population=num2cell(file{3})
sortedStates=sortrows(State)
n=length(State)
regions=struct('State',State,...
'Capital',Capital,...
'Population',Population)
for k=1:n;
region=sortedStates(k);
state_name={regions.State};
state_reference=strcmpi(state_name,region);
state_info=regions(state_reference)
end
I hope I'm making myself clear.
Use this to sort the cell array read in (no conversion needed), then write to file with this.
With respect to your sorting issue, The function SORT will return as its second output a sort index which can be used to apply the same sort order to other arrays. For example, you could sort your arrays before you create your structure array:
[sortedStates,sortIndex] = sort(State);
regions = struct('State',sortedStates,...
'Capital',Capital(sortIndex),...
'Population',Population(sortIndex));
Or you could apply your sorting after you create your structure array:
regions = struct('State',State,...
'Capital',Capital,...
'Population',Population);
[~,sortIndex] = sort({regions.State});
regions = regions(sortIndex);
However, I'm not sure what you mean when you say "I want it to be an array so I can write to a file."